1. Field of the Invention
The present invention relates to data communication management; and particularly to a method and system for data communication handoff across heterogeneous wireless networks.
2. Description of the Related Art
Wireless telephony service providers offer not only voice calling but also General Packet Radio Service (GPRS) to enable the data packet transmission via a mobile terminal. Although GPRS is feasible in mobile data transmission, the transmission rates typically do not exceed 56 Kbs and the costs remain expensive. Advances in wireless local area network (WLAN) technology have led to the emergence of publicly accessible WLANs (e.g., “hot spots”) at airports, cafes, libraries and other public facilities. The WLAN uses radio frequency transmission to communicate between roaming mobile terminals and access points (or base stations). The relatively low cost to implement and operate a WLAN, as well as the available high bandwidth (usually in excess of 10 Megabits/second) has made the WLAN an idea wireless access infrastructure.
“Cell” is the basic geographic unit of a wireless telephony system. A city or county is divided into smaller cells, each of which is equipped with a low-powered radio transmitter/receiver. The cells can vary in size depending on terrain, capacity demands, or other conditions. By controlling the transmission power, the radio frequencies assigned to one cell can be limited to the boundaries of that cell.
In a hybrid wireless communication environment, a cell may contain multiple WLANs. When a mobile terminal attaching to a wireless telephony network enters a WLAN in one cell, in the ideal situation, the data transmission is handled by the WLAN without disrupting the data communication. In order to accommodate wireless telephony networks and WLANs, Subscriber Identity Module (SIM) based authentication using Extensible Authentication Protocol Over LAN (EAPOL) has been introduced to provide a unified protocol for communication between different types of wireless networks. Although the solution is feasible, the interrogation information transmitted back and forth between a WLAN and a wireless telephony network is time consuming, and disruptive to data communication.
In view of the above limitations, a need exists for a system and method of data communication handoff to provide an efficient authentication mechanism for a hybrid wireless network environment.